add several exception class
bug fix GtSubProc.java
fix DShellGrammer
fixed messages
enable StrictMode
fixed messages
refactoring ClassDecl2
adding error handling to TypeVarDecl
replacing GtSyntaxTree.ConstValue with ParsedValue
adding NewNode
fix js codegen
fix infinite loop
fix ParseFileOp
fix ExpandPath
fix cast
bugs fixed at error messaging
bugs fixed at duplicated abstract class
adding ClassAbstractDeclTest.green
adding NewNode.ToConstValue
refactoring GtType